Electric heater.



J. G. LOGAN.

1 ELECTRIC HEATER.

APPLICATION FILED un. 20, 1909.

Patented May 10, 1910.

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JUDSON C. LOGAN, 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATER.

To all whom it may concern:

Be it known that I, JUDsoN C. LOGAN, a citizen of the United States,residing at Pittsfield, county of Berkshire, State of Massachusetts,have invented certain new and useful Improvements in Electric Heaters,of which the following is a specification.

My invention relates to electric heaters and has for its object theprovision of a device of this character in which more than one heat canbe developed in the windings in a simple and efficient manner.

In carrying out my invention, I employ a plurality of rings ofinsulating material such as mica or the like, upon which the resistanceconductors are wound. These rings are placed one within and spaced fromthe other. Two independent resistance conductors are then wound upon thering so as to extend throughout the area of both of them. The conductorsare wound adjacently and have a common terminal in addition to anindependent terminal for each conductor, the arrangement being such thatcurrent may be passed through one conductor or'through the two inparallel, as desired. In either case, the current will extend over andheat uniformly the entire surface of both rings.

In the accompanying drawing, in which I have shown my invention embodiedin concrete form, Figure 1 represents a plan view of the heating unit;Fig. 2 represents a sectional view of an electric stove having myinvention applied thereto; and Fig. 3 is a diagram of the circuitconnections.

Referring to the drawings, 10 represents an outer ring of insulatingmaterial, such for instance as mica or the like, and 11 represents aninner ring of similar material spaced from the outer. Two resistanceconductors 12 and 13 are wound upon these rings. These conductors are inthe form of resistance Lib mand are of high resistanceiiiatfiar;uch""ror instance as that disposed in the patent of Dempster,No. 901,428, Oct. 20, 1908. These two resistance conductors have acommon terminal at 14. Starting from this terminal, the resistanceconductor 13 is wound first upon the outer ring in one direction andthen crosses over to the inner ring and is wound thereon in an oppositedirection coming back to the terminal 15 arranged on the outer ring.Conductor 12 starting from the terminal 14 is wound Specification ofLetters Patent.

Application filed March 20, 1909.

Patented May 10, 1910.

Serial No. 484,692.

around the inner ring in one direction and then crosses over to theouter ring and is wound around it in an opposite direction, ending inthe terminal 16 on the outer ring. The two windings thus have a commonterminal at 14: and independent terminals at 15 and 16 respectively. Bythis arrangement the terminals may be connected so that either one ofthe conductors is connected in circuit alone or the two may be connectedin parallel. This may be done by the means shown in Fig. 3, theparticular arrangement of which forms no part of my invention. In thisarrangement the terminal 15 is compound, being arranged to contact withboth resistances 12 and 13 as shown. By applying the two socketterminals to contacts 14L and 16, the resistance 12 will be connected incircuit, while if socket terminals are applied to contacts 14 and 15 theresistances 12 and 13 will be connected in parallel. In other words, theresistance conductor would extend through the entire area of the surfaceto be heated in either case.

In Fig. 2 I have shown the heating unit applied to an electric stove inwhich the two rings are clamped between two sheets of mica 17 by ametallic casing 18. This is secured to the insulating ring 19 and theter-.

minals brought down to the terminal pins. The mica is very muchexaggerated in thickness in the drawing for clearness. In practice it isonly a few mills thick.

IVhile I have shown my invention embodied in concrete form for purposesof illustration, it should be understood that I do not limit myinvention thereto, since various modifications thereof still suggestthemselves to those skilled in the art without departing from the spiritof my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. An electric heating unit comprising concentric spaced rings ofinsulation having two independent resistance conductors wound thereonadjacent each other and having three terminals, one of which is commonto both windings.

2. An electric heater comprising concentric spaced rings of insulationhaving two independent resistance conductors wound thereon from a commonterminal, one of Which is Wound first on the inner ring and then on theouter While the other is wound first on the outer and then on the innerring.

8. An electric heater comprising an inner and an outer ring ofinsulating material and a plurality of independent resistance conductorsWound upon said rings.

4-. An electric heater comprising an inner and an outer ring ofinsulating material and 10 a plurality of independent resistanceconductors Wound thereon adjacent each other and having a terminalcommon to both Wind ings.

In Witness whereof, I have hereunto set my hand this 18th day of March,1909.

JUDSON G. LOGAN.

Witnesses:

P. A. SMITH, F. G. LARAMEE.

